1. Field of the Invention
The present invention relates to a novel triphenol type compound. More particularly it relates to a novel triphenol type compound which is useful as a branching agent for polycarbonate. The present invention also relates to a novel polycarbonate and the production process thereof using the above-mentioned triphenol type compound as a branching agent.
2. Description of the Related Art
Polycarbonate is a synthetic resin which has been widely used in industry and is usually produced by the reaction between a divalent phenol such as 2,2-bis(4'-hydroxyphenyl)propane (hereinafter sometimes abbreviated as bisphenol A) and a carbonic acid derivative such as phosgene.
Although a polycarbonate produced from bisphenol A has excellent characteristics such as excellent impact resistance, small hygroscopicity, stable heat resistance and weathering resistance, since it behaves as a Newtonian fluid in a molten state, a great stress is required for obtaining a desired extruded amount and the melt elasticity or melt strength intimately correlated therewith is low, whereby a problem has arisen in that it is difficult to produce a large scale hollow molding.
To solve this problem, it has been proposed to permit a trivalent phenol such as phloroglucinol 4,6-dimethyl-2,4,6- tri(4'-hydroxyphenyl)heptene-2, 4,6-dimethyl-2,4,6-tri(4'-hydroxyphenyl) heptane or 2,6-bis(2'-hydroxy-5'-methylbenzyl)-4-methylphenol to be co-present in an amount of 0.01 mole % or more based on divalent phenol during production of polycarbonate, thereby branching the polycarbonate obtained, as disclosed in U.S. Pat. Nos. 3,635,895 or 3,544,514.
These thermoplastic branched polycarbonates obtained by permitting trivalent phenol to be co-present during the production of polycarbonate indeed exhibit non-Newtonian flow characteristics in a molten state, and their melts have an improved resistance to deformation. However, there are problems in that, compared with conventional polycarbonates prepared from bisphenol A, the moldings have an inferior color and transparency, and that resistance to deformation of the melt is not necessarily satisfactorily improved.